Investigation of the microstructure,mechanical and wear performance of friction stir-processed AA6061-T6 plate reinforced with B 4 C particles surface composite

In this work, friction stir processing (FSP) was used to successfully embed boron carbide (B₄C) particles into an aluminum matrix (AA6061-T6). Four specimens of aluminum 6061 composite reinforced with 4%, 6%, 8%, and 10% volume fraction of B₄C were manufactured. The effects of B₄C particles volume fraction on microstructure, mechanical and wear properties are investigated. The microstructural investigations demonstrated that a rise in the volume % of reinforcement greatly decreased the matrix grain size. The manufactured AA6061-T6 loaded with B₄C surface composites demonstrated homogeneous B₄C particle dispersion, with no significant particle clustering in the stir zone. In addition, it was established that increasing the volume fraction of B₄C particles promoted grain refinement, increased hardness, and tensile strength. X-ray diffraction (XRD) was used to identify the reinforcement dispersion. For AA6061-T6 with 10% B₄C particles, a maximum hardness value of 163 HV was obtained in the stir zone. Maximum yield strength of 165 MPa and ultimate tensile strength of 220 MPa were attained by AA6061-T6 with 10% B₄C particles, which is an improvement of 21% over the specimen FSP without reinforcement. The strengthening of the grain refining was attributed for the increase in hardness and strength. The ductility was reduced by the incorporation of more B₄C particles. Comparing the surface composite loaded with B₄C to unreinforced friction stir processing and AA6061-T6 as received, it demonstrated superior wear resistance.